Emissive shader does not change much in changes of orders of magnitudes
The problem is the light clamping setting.

Set &quot;Direct Light&quot; to 0 to fix the power issue.
Setting the clamping to 1 means that any value brighter than 1 is clipped (or ignored), therefore it doesn't matter if the lights are set to an intensity of 1 or 1 million. Setting it to 0 means that the lights are un-clamped, therefore using their real values.
Read: What is Clamp Direct/Indirect?
Additionally, I would recommend setting the color management to filmic for more realistic tone mapping. Standard transform is usually used for video editing.